Worksheet Overview

QUESTION 1 of 10

Energy is all around us: we use it, we make it and it is never created or destroyed, but changes forms.

We take chemical energy from the food we eat; or actually, we use the food we eat to make our own energy in a process called respiration. Energy in food is measured in calories (cal), and you may know people that count how many calories they eat each day. In reality, the calories that people count are actually kilocalories (kcal). One kcal contains one thousand cal. The amount of energy people need from food each day varies a lot according to age, lifestyle, pregnancy, general health, gender and other possible factors. Roughly, for an adult 2000-2200 calories are the required daily intake.

This is a typical content label on a food package; it breaks down the product into its components, for example protein, carbohydrate and fat.

It is possible to determine the amount of energy in different types of food in a simple experiment. You need different types of food, e.g. crisps and bread, cut up in small pieces. You literally have to burn them under a boiling tube with a certain amount of water and measure how much the temperature rises. The more the temperature of the water increases, the more energy has been released from that type of food.

Be aware that this is an experiment that you may do at school, but you should not try it at home by yourself. The energy released by each food type is calculated using the following formula:

energy released from food per gram in Joules

mass of water (g) × temperature rise (ºC) × 4.2

=

mass of food sample (g)

4.2 is a constant number (this means it never changes) and is related to the capacity of water to have its temperature raised.

You may have noticed that, although it was mentioned earlier that calories are used as a unit for energy in everyday life, in physics energy is measured in joules (J). Protein energy ranges from 2.44 kcal/g to 4.36 kcal/g. Fat has 8.37 kcal/g to 9.02 kcal/g and carbohydrates have 2.70 kcal/g to 4.16 kcal/g.

What type of energy is stored in food?

kinetic

heat

chemical

What process does our body use to make energy from food?

photosynthesis

respiration

What is the everyday term used to quantify energy in food?

calories

joules

In reality, is 'calories' the correct scientific term to measure energy in food?

yes

no

When people count the calories they eat every day, what are they actually measuring, if the term 'calories' is not scientifically correct?

What is the general daily intake of calories for a healthy adult?

500-1000

2000-2200

3000-3200

You are doing an experiment to measure energy in different types of food. What is it that you actually measure in order to determine the amount of energy?

mass of water

temperature rise

amount of fire

What is the typical unit for energy in physics? Type the whole word in the box below.

What is the energy content of protein in kcal per gram?

2.44 kcal/g to 4.36 kcal/g

8.37 kcal/g to 9.02 kcal/g

2.70 kcal/g to 4.16 kcal/g

What is the energy content of fat in kcal per gram?

2.44 kcal/g to 4.36 kcal/g

8.37 kcal/g to 9.02 kcal/g

2.70 kcal/g to 4.16 kcal/g

ANSWERS

Question 1

What type of energy is stored in food?

CORRECT ANSWER

chemical

EDDIE SAYS

Energy stored in food is chemical.

ANSWERS

Question 2

What process does our body use to make energy from food?

CORRECT ANSWER

respiration

EDDIE SAYS

Our body makes its own energy from food in a process called respiration.

ANSWERS

Question 3

What is the everyday term used to quantify energy in food?

CORRECT ANSWER

calories

EDDIE SAYS

Energy in food is measured in calories in everyday life.

ANSWERS

Question 4

In reality, is 'calories' the correct scientific term to measure energy in food?

CORRECT ANSWER

no

EDDIE SAYS

No, 'calories' is used to make things easier.

ANSWERS

Question 5

When people count the calories they eat every day, what are they actually measuring, if the term 'calories' is not scientifically correct?

CORRECT ANSWER

kilocalorieskcal

EDDIE SAYS

Calories measured in food are actually kilocalories, to be scientifically correct. The abbreviation for kilocalories is kcal.

ANSWERS

Question 6

What is the general daily intake of calories for a healthy adult?

CORRECT ANSWER

2000-2200

EDDIE SAYS

A healthy adult should generally consume 2000-2200 calories a day. However, this amount may vary according to age, gender, lifestyle and other factors.

ANSWERS

Question 7

You are doing an experiment to measure energy in different types of food. What is it that you actually measure in order to determine the amount of energy?

CORRECT ANSWER

temperature rise

EDDIE SAYS

The temperature rise is measured every time you burn a different food sample.

ANSWERS

Question 8

What is the typical unit for energy in physics? Type the whole word in the box below.

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